The present invention relates to a process for the production of a molded body having a pressed core of solid inert particles which are coated with a thermoset phenolic resin.
A body of this kind is described for use as a decorative building panel in U.S. Pat. No. 4,503,115. The building panel comprises a pressed core of wood fibers which are coated with a thermoset phenol-formaldehyde resin. In the preparation of this molded body, the wood fibers are coated or impregnated with an aqueous alkaline solution of the thermosetting phenol-formaldehyde resin and the coated wood fibers are hot-pressed, the resin being cured in the process.
This method has various disadvantages. It is for example necessary for the solution of the phenol-formaldehyde resin to be prepared separately from the individual components, in a preceding stage. The solvent used for the still soluble phenol-formaldehyde resin must be removed from the wood fibers in a special process stage prior to pressing. This involves the risk that, together with the solvent, volatile low-molecular weight reaction products of phenol and formaldehyde and still unreacted phenol and formaldehyde also are removed. Consequently, an expensive purification of waste water and exhaust air is required. When hot-pressing the wood fibers there is furthermore a risk that the water formed as a result of the reaction of formaldehyde escapes abruptly and thus bursts the pressed body obtained.